Energy conversions . can lose energy as sound can be 100 percent efficient if controlled properly are calculated by multiplying useful energy by the total amount of energy

are calculated by multiplying useful energy by the total amount of energy

Explanation:

The energy conversions are never 100 percent efficient. This is because the energy originally is converted into a mixture of the useful and not useful energy. For example, gasoline in the car is converted to motion, sound and friction. The later two (sound and friction) are energies but are less useful. Thus, in this case, the energy conversion is not 100 % efficient. Thus, the energy efficiency equation comes into play. This is given as the ratio of the useful energy to the total energy. It is a fraction.  

answer by yourhope:

how do models compare to real-world objects?

d. most models represent a real-world object in a simpler way.

: )

20 drops hope this